We have been building with radiant floors since the early 1990s. When they are designed right, nothing is more comfortable. When they are not, you get a house where the boiler runs all day, the pipes at the manifold are hot, and the floor is barely warm.
The good news is that most radiant problems can be fixed without tearing up the floor. Here is how to find out which problem you have.
A floor can only get so warm before it is uncomfortable. Rooms with lots of glass can need more heat than the floor can deliver. The heat loss shows it.
Air blocks flow. Gurgling, cold loops and hot supply pipes are the signs. Bleed it out.
Long loops starve the far end. Unequal loops send all the water down the short ones. See manifold layout.
Wide spacing leaves cold stripes and limits output.
The heat goes into the ground instead of the room. See radiant slab design.
Outdoor reset curve too low, big night setbacks on a slow slab, or a circulator that is too small.
Cheapest fix, and a common one.
Every loop valve and actuator actually open?
Running, right speed, sized for the loops it serves.
Too low a water temperature on cold days. Your installer can adjust it.
A slab takes hours to recover. Small setbacks or none.
Thick carpet and pad block the heat.
If it is still short after the basics, compare the room-by-room heat loss with what your floor can deliver. That tells you whether to fix the floor, the house, or add heat.
Set flows so every loop gets its share.
Within what the floor and finish can take.
A panel radiator, fan coil or ductless head where the floor cannot keep up.
Better windows, air sealing or insulation can bring the room’s load down to what the floor can do.
Every one of these problems is decided at design: the heat loss, tube spacing, loop lengths, manifold location, slab insulation and the heat source. See radiant floor design and boiler sizing.
Radiant-only houses still need ventilation, which goes on the ventilation summary (RMVDS) for your permit.
Radiant not keeping up? Send us the floor plan and what you know about the system. We show you where the shortfall is.
Get Free Quote →Usually one of three things: the house loses more heat than the floor can put out, the water is not getting through the loops properly, or the controls are set wrong. The heat loss tells you which. Without it, everyone is guessing.
Hot water is not moving through the floor. Air in the loops, a closed manifold valve, loops that are too long, or a circulator that is too small. Bleed the air and check the manifold before anything else.
No. The floor can only get so warm before it is uncomfortable to stand on. If a room’s heat loss is more than the floor can deliver at a comfortable temperature, it needs help: better insulation, or a second heat source in that room.
Yes. Thick carpet and pad act like a blanket over the tubing. Hardwood slows it down too. The floor finish has to be part of the design, not a surprise after.
Slab radiant reacts slowly. Big setbacks mean hours of cold before it catches up. Most slab systems are happiest with small or no setbacks.
Often yes, without tearing up the floor: bleeding and balancing, adjusting the outdoor reset, a bigger circulator, or adding heat to the rooms that fall short. Sometimes the fix is in the envelope, not the floor.
Send your floor plan, floor finishes and what you know about the tubing and boiler. We calculate the heat loss so you can see which rooms the floor can carry and which need help.